Synthetic augmentation of bilirubin metabolism in human pluripotent stem cell-derived liver organoids

Summary

UGT1A1 (UDP glucuronosyltransferase family 1 member A1) is the primary enzyme required for bilirubin conjugation, which is essential for preventing hyperbilirubinemia. Animal models lack key human organic anion transporting polypeptides with distinct epigenetic control over bilirubin metabolism, necessitating a human model to interrogate the regulatory mechanism behind UGT1A1 function. Here, we use induced pluripotent stem cells to develop human liver organoids that can emulate conjugation failure phenotype. Bilirubin conjugation assays, chromatin immunoprecipitation, and transcriptome analysis elucidated the role of glucocorticoid antagonism in UGT1A1 activation. This antagonism prevents the binding of transcriptional repressor MECP2 at the expense of NRF2 with associated off-target effects. Therefore, we introduced functional GULO (L-gulonolactone oxidase) in human organoids to augment intracellular ascorbate for NRF2 reactivation. This engineered organoid conjugated more bilirubin and protected against hyperbilirubinemia when transplanted in immunosuppressed Crigler-Najjar syndrome rat model. Collectively, we demonstrate that our organoid system serves as a manipulatable model for interrogating hyperbilirubinemia and potential therapeutic development.

Graphical abstract

Highlights

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  HLOs are amenable for studying mediated bilirubin conjugation

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  HLOs inform the glucocorticoid-mediated epigenetic regulation of UGT1A1

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  Synthetic introduction of murine GULO in HLOs more efficiently conjugates bilirubin

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  Engineered HLO transplantation alleviates the symptoms of Crigler-Najjar syndrome model

Abstract

This paper describes the development of pluripotent stem cell-derived human liver organoid (HLO) models to study UGT1A1 gene regulation and function. We engineered active GULO (murine gulonolactone oxidase) expressing HLO to augment therapeutic potential, thus alleviating symptoms in Crigler-Najjar syndrome model rats upon transplantation.